This invention relates to a method of making thermoset dicyclopentadiene (sometimes hereinafter referred to as DCPD) polymer and the product so produced. In particular, it relates to a method of polymerizing DCPD which involves the incorporation of a halogen containing hydrocarbyl additive into the catalyst system and the product so produced.
Thermoset poly(DCPD) is well suited for a wide variety of applications, particularly as an engineering plastic. The number of applications has been somewhat limited, however, because of the distinctive odor of the residual DCPD monomer. Consequently, there is a desire to reduce the level of residual monomer in the thermoset product.
One of the great advantages offered by poly(DCPD) is that it can be made via reaction injection molding (sometimes hereinafter referred to as RIM). Reaction injection molding is a process for in-mold polymerization which involves the mixing of two or more low viscosity reactant streams. The combined streams are then injected into a mold where they quickly set up into a solid infusible mass. For a particular catalyst system to be of use with RIM, certain requirements must be met:
(1) the individual reactant streams must be stable and must have a reasonable shelf-life under ambient conditions;
(2) it must be possible to mix the reactant streams thoroughly without their setting up in the mixing head;
(3) when injected into the mold, the materials must react rapidly to form a solid; and
(4) any additives incorporated into the catalyst system must not interfere with the above requirements.
In addition to not adversely affecting the reaction it is desired that any additive actually serve to increase the reaction's efficiency such as making it possible to use less catalyst and making the catalyst system less sensitive to the ratio of activator to catalyst.
U.S. application Ser. No. 342,453, filed Jan. 25, 1982, now U.S. Pat. No. 4,400,340, discloses a thermoset poly(dicyclopentadiene) and a method for making the same. U.S. Pat. No. 3,816,384 discloses that the molecular weight of non-thermoset polyalkenamers, including poly(dicyclopentadiene), can be controlled by polymerizing in the presence of an ethylenically unsaturated halogenated hydrocarbon. Neither of these references discloses the synthesis of a thermoset poly(dicyclopentadiene) with a metathesis-catalyst system where the catalyst system has incorporated a halogen containing hydrocarbyl additive.